This invention relates generally to gas turbine engines, more particularly to combustors used with gas turbine engines.
Known turbine engines include a compressor for compressing air which is suitably mixed with a fuel and channeled to a combustor wherein the mixture is ignited within a combustion chamber for generating hot combustion gases. More specifically, at least some known combustors include a dome assembly, a cowling, and liners to channel the combustion gases to a turbine, which extracts energy from the combustion gases for powering the compressor, as well as producing useful work to propel an aircraft in flight or to power a load, such as an electrical generator. Moreover, at least some known combustors include ignition devices, such as ignitors, primer nozzles, and/or pilot fuel nozzles, which are used during pre-selected engine operations to facilitate igniting the mixture within the combustion gases.
Known ignition devices extend through an annular tower extending outwardly from the combustor, such that at least a portion of such ignition devices is exposed to high temperatures generated within the combustion chamber. Moreover, within recouperated engines, generally such ignition devices are exposed to higher temperatures than similar devices used with non-recouperated engines. Accordingly, because of the orientation and relative position of the primer nozzle within the combustor, at least some known ignition devices are cooled. Moreover, at least some known ignition devices include tip shrouds which are also cooled and extend circumferentially around an injection tip of the primer nozzles. However, in at least some known primer nozzles, the cooling flow to the tip shrouds is unregulated such that if a shroud tip burns off during engine operation, cooling air flows unrestricted past the injection tip, and may adversely affect primer nozzle performance.
Furthermore, because of the increased combustion temperatures generated within such recouperated engines, generally the combustor towers used within recouperated engines are taller and wider than those used in non-recouperated engines. Although the increased size of such towers facilitates reducing an amount of thermal interference created between the tower and the ignition device, the increased size of such towers may enable high temperature gases to recirculate in a gap defined between the tower and the ignition device. Over time, the recirculation of high temperature gases through the tower assembly may result in damage to the tower assembly and/or to the ignition device.